The present invention relates to a video data transmitting method employed when video data is transmitted from a transmitter to a receiver and more particularly, to a video data transmitting method which can reduce a loss in the data by generating a video data from at least two video data having different resolution and then transmitting the generated video data as one unit of data for transmission.
A digital video input device such as a conventional type of CCD camera has CCDs (solid-state image pickup devices or light-receiving elements) arranged in a matrix. The CCDs perform photoelectric conversion based on amplitude of inputted light. The data obtained by the CCDs is scanned at a prespecified sampling cycle to obtain voltage values. The analog voltage values are converted into digital data, and inputted as video data to a receiver.
Thus, video data inputted in one scan represents a data for all of the CCDs arranged in the matrix. In other words, all the CCDs arranged in the matrix form are considered as forming one screen, and one screenful of video data is inputted in one scan. For example, when the digital video input device is a digital camera, one screenful of video data inputted in one scan corresponds to a sheet of static image. When the digital video input device is a video camera, tens of scan per unit time are successively performed and tens of screenful of video data per unit time (namely, moving images) are inputted.
When the video data is transmitted, for example, from a digital input device to a display unit such as a CRT or from a storing device (or a storage medium) in which the video data is stored to other equipment, video data is outputted in the same order as that of scanning and is received by a receiver for displaying or storing therein. When video data is to be transmitted through a communication line, it is compressed or divided into frames according to a communication protocol for transmission, however, the original data is the same.
With the conventional technology described above, if data is lost during transmission due to any reason, incomplete image data is received by a receiver because information (data indicating density or brightness) for one pixel or area transmitted once or transmitted for transfer of one image data is grouped into one unit.
Especially, when the transmitter is a CCD camera and the receiver is a memory device or the like, a data is transmitted from the CCD camera only once, this may create a serious problem when a video data having a missing portion is stored in the memory device. In addition, when the transmitter is a scanner and the receiver is a printer, a serious problem may also come up if video data (image data) having a missing portion is outputted, since the video image received by the printer is outputted onto a paper in real time.
It is an object of the present invention to provide, for solving the problems described above, a video data transmitting method that can reduce data loss.
Other objects and features of this invention will become clear from the following description with reference to the accompanying drawings.
In the transmitting method of the present invention, at least two types of video data having different resolution is generated from the original video data, and the two types of video data is transmitted as one data, so that it is possible to provide a video data transmitting method which can reduce loss of data.
In the transmitting method of the present invention, a screenful of video data is dividing into a plurality of first rectangular areas, a first video data corresponding to each of the first rectangular area is generating from the video data in that particular first rectangular area, many of the first rectangular areas are grouped into a plurality of second rectangular areas; a second video data corresponding to each second rectangular area is generating from the first video data in that second rectangular area, the first and second video data is combining as a unit of video data for transmission and the combined video data is transmitted to the receiver, it is checked whether each of the first video data comprising each of the second rectangular area exists without any data loss, and when each of the first video data comprising each of the second rectangular area exists without any data loss, the first video data is considered as inputted video, and when a portion of the first video data comprising each of the second rectangular area is found to be lost, then the second video data is considered as an inputted video data, so that it is possible to provide a video data transmitting method which can reduce loss of data.
In the transmitting method of the present invention, a screenful of video data is dividing into a plurality of first rectangular areas, a first video data corresponding to each of the first rectangular area is generating from the video data in that particular first rectangular area, many of the first rectangular areas are grouped into a plurality of second rectangular areas; a second video data corresponding to each second rectangular area is generating from the first video data in that second rectangular area, the first and second video data is combining as a unit of video data for transmission and the combined video data is transmitted to the receiver, it is checked whether each of the first video data comprising each of the second rectangular area exists without any data loss, and when each of the first video data comprising each of the second rectangular area exists without any data loss, the first video data is considered as inputted video, and when a portion of the first video data comprising each of the second rectangular area is found to be lost, then deciding the first and second video data as an inputted video data and generating a screenful of video data from each of the first and second video data, so that resolution is prevented from its lowering and in addition, loss of data can be reduced.